CBSE Class 11 Chemistry Sample Paper Set 3

1. Express 32.392800 to four significant figures.

2. Write the correct symbol for the nucleus with an

          a) atomic number 56 and mass number 138

          b) atomic number 26 and mass number 55.

3. Using periodic table, identify

          a) an element that would tend to gain two electrons

          b) an element that would tend to lose two electrons.

4. The critical temperature for carbon dioxide and methane are 31.1°C and – 81.9°C respectively. Which of these has strong intermolecular forces and why?

5. In normal egg → hard boiled egg, state whether order has increased or decreased and consequently the direction of change of entropy of the system.

6. Arrange the following metals in the order in which they displace each other from the solution of their salts. Al, Cu, Fe, Mg and Zn.

7. Give the balanced ionic reaction of Mn³⁺ on disproportionation.

8. Justify that the reaction: 2Na(s) + H₂(g) →2NaH(s) is a redox reaction.

9. Write the empirical formulas of the compounds having the molecular formulas:

          a) C₆H₆          b) C₆H₁₂  

          c) H₂O₂          d) H₂O.

10. The symbols of  79 

                               Br

                            35Br  and

₃₅Ba are not acceptable. Why?

11.Why is benzene extra-ordinary stable though it contains three double bonds?

12. Although geometries of ammonia and water molecules are distorted tetrahedral, bond angle in water is less than that of ammonia. Why?

13. Explain the physical significance of van der Waals parameters.

14. Consider the reaction: A + B →C + D.a) If the reaction is endothermic and spontaneous in the direction indicated, then what would be the sign of ΔG and ΔS.

15. Can equilibrium be achieved between water and its vapour in an open vessel? Explain your answer and say what happens eventually.

16. What will be the conjugate bases for the following Bronsted acids: a) HF b) H₂SO₄ and c) HCO₃ ^-?

17. The electrode reduction potentials of four metallic elements A, B, C and D are + 0.79, - 0.74, 1.08 and – 0.31 V. Arrange these in order of decreasing electropositive character. Give reasons.

18. What is hydride gap? Why is heavy water used in nuclear reactors?

19. Explain open, isolated and closed systems with an example.

20. If water vapour is assumed to be a perfect gas, molar enthalpy change for vapourisation of 1 mol of water at 1bar and 100°C is 41kJ mol–¹. Calculate the internal energy change, when

            (i) 1 mol of water is vaporised at 1 bar pressure and 100°C

            (ii) 1 mol of water is converted into ice.

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